Choropleth map of U.S. states showing the change in gas prices from August 2022 to August 2023. The average price per regular unleaded gallon increased significantly in 10 states, mostly in the South and Central U.S. Prices in Iowa increased the most, by 6.1%. Prices in Northeast and West Coast states (apart from Washington) decreased the most, with prices in Idaho dropping nearly 15% to $3.98 per gallon.